Controlled compliance fine pitch interconnect

ABSTRACT

A method and apparatus for achieving a very fine pitch interconnect between a flexible circuit member and another circuit member with extremely co-planar electrical contacts that have a large range of compliance. An electrical interconnect assembly that can be used as a die-level test probe, a wafer probe, and a printed circuit probe is also disclosed. The second circuit member can be a printed circuit board, another flexible circuit, a bare-die device, an integrated circuit device, an organic or inorganic substrate, a rigid circuit and virtually any other type of electrical component. A plurality of electrical contacts are arranged in a housing. The electrical contacts may be arranged randomly or in a one or two-dimensional array. The housing acts as a receptacle to individually locate and generally align the electrical contacts, while preventing adjacent contacts from touching. The first ends of the electrical contacts are electrically coupled to a flexible circuit member. The electrical contacts are free to move along a central axis within the housing. The second ends of the electrical contacts are free to electrically couple with one or more second circuit members without the use of solder.

This application is a 371 of PCT/US00/20748 filed Jul. 31, 2000 whichclaims benefit to provisional application Ser. No. 60/146,825 filed Aug.2, 1999.

FIELD OF THE INVENTION

The present invention is directed to a method and apparatus forachieving a very fine pitch, solderless interconnect between a flexiblecircuit member and another circuit member, and to an electricalinterconnect assembly for forming a solderless interconnection withanother circuit member.

BACKGROUND OF THE INVENTION

It is desirable to probe test each die or device under test (DUT) beforethe wafer is cut into individual intergrated circuit die or beforepackaging. Die testing often needs to be performed at high speed or highfrequency, for example 100 MHz data rate or higher. The probe cards thatsupport a plurality of probe needles must provide reliable electricalcontact with the bonding pads of the DUT. The shank of the probe needleis typically 0.005 inches to 0.010 inches in diameter.

One test probe technique is known as the Cobra system, in which theupper ends of the probe needles are guided through a rigid layer of aninsulating material. The upper ends of the individual probe needles areelectrically connected to suitable conductors of an interface assemblythat is connected to an electrical test system. Each of the needles iscurved and the lower ends pass through a corresponding clearance hole ina lower rigid layer or template of insulating material. The bottom endsof the needles contact the bonding pads on the wafer being tested. Thelength of the probe needles can result undesirable levels of groundnoise and power supply noise to the DUT. Additionally, the epoxy orplastic rigid layers have large coefficients of thermal expansion andcause errors in the positioning of the needle probes.

Another draw-back of current test probe technology is that it can oftennot accommodate fine pitches. For example, wafer probes typicallyrequire a target contact area of about 70 micrometers by 70 micrometers.Flip-chip architecture has terminals on the order of 10 micrometers by10 micrometers, and hence, can not effectively be tested using waferprobe technology. Consequently, integrated circuits in flip-chiparchitectures can generally be tested only after packaging is completed.The inability to wafer probe integrated circuits used in flip-chiparchitecture results in production time delays, poor yields and aresultant higher cost.

Many of the problems encountered in testing electrical devices alsooccur in connecting integrated circuit devices to larger circuitassemblies, such as printed circuit boards or multi-chip modules. Thecurrent trend in connector design for those connectors utilized in thecomputer field is to provide both high density and high reliabilityconnectors between various circuit devices. High reliability for suchconnections is essential due to potential system failure caused bymisconnection of devices. Further, to assure effective repair, upgrade,testing and/or replacement of various components, such as connectors,cards, chips, boards, and modules, it is highly desirable that suchconnections be separable and reconnectable in the final product.

Pin-type connectors soldered into plated through holes or vias are amongthe most commonly used in the industry today. Pins on the connector bodyare inserted through plated holes or vias on a printed circuit board andsoldered in place using conventional means. Another connector or apackaged semiconductor device is then inserted and retained by theconnector body by mechanical interference or friction. The tin leadalloy solder and associated chemicals used throughout the process ofsoldering these connectors to the printed circuit board have come underincreased scrutiny due to their environmental impact. Additionally, theplastic housings of these connectors undergo a significant amount ofthermal activity during the soldering process, which stresses thecomponent and threatens reliability.

The soldered contacts on the connector body are typically the means ofsupporting the device being interfaced by the connector and are subjectto fatigue, stress deformation, solder bridging, and co-planarityerrors, potentially causing premature failure or loss of continuity. Inparticular, as the mating connector or semiconductor device is insertedand removed from the present connector, the elastic limit on thecontacts soldered to the circuit board may be exceeded causing a loss ofcontinuity. These connectors are typically not reliable for more than afew insertions and removals of devices. These devices also have arelatively long electrical length that can degrade system performance,especially for high frequency or low power components. The pitch orseparation between adjacent device leads that can be produced usingthese connectors is also limited due to the risk of shorting.

Another electrical interconnection method is known as wire bonding,which involves the mechanical or thermal compression of a soft metalwire, such as gold, from one circuit to another. Such bonding, however,does not lend itself readily to high-density connections because ofpossible wire breakage and accompanying mechanical difficulties in wirehandling.

An alternate electrical interconnection technique involves placement ofsolder balls or the like between respective circuit elements. The solderis reflown to form the electrical interconnection. While this techniquehas proven successful in providing high-density interconnections forvarious structures, this technique does not facilitate separation andsubsequent reconnection of the circuit members.

An elastomer having a plurality of conductive paths has also been usedas an interconnection device. The conductive elements embedded in theelastomeric sheet provide an electrical connection between two opposingterminals brought into contact with the elastomeric sheet. Theelastomeric material must be compressed to achieve and maintain anelectrical connection, requiring a relatively high force per contact toachieve adequate electrical connection, exacerbating non-planaritybetween mating surfaces. Location of the conductive elements isgenerally not controllable. Elastomeric connectors may also exhibit arelatively high electrical resistance through the interconnectionbetween the associated circuit elements. The interconnection with thecircuit elements can be sensitive to dust, debris, oxidation,temperature fluctuations, vibration, and other environmental elementsthat may adversely affect the connection.

The problems associated with connector design are multiplied whenmultiple integrated circuit devices are packaged together in functionalgroups. The traditional way is to solder the components to a printedcircuit board, flex circuit, or ceramic substrate in either a bare diesilicon integrated circuit form or packaged form. Multi-chip modules,ball grids, array packaging, and chip scale packaging have evolved toallow multiple integrated circuit devices to be interconnected in agroup.

One of the major issues regarding these technologies is the difficultyin soldering the components, while ensuring that reject conditions donot exist. Many of these devices rely on balls of solder attached to theunderside of the integrated circuit device which is then reflown toconnect with surface mount pads of the printed circuit board, flexcircuit, or ceramic substrate. In some circumstances, these joints aregenerally not very reliable or easy to inspect for defects. The processto remove and repair a damaged or defective device is costly and manytimes results in unusable electronic components and damage to othercomponents in the functional group.

Multi-chip modules have had slow acceptance in the industry due to thelack of large scale known good die for integrated circuits that havebeen tested and burned-in at the silicon level. These dies are thenmounted to a substrate which interconnect several components. As thenumber of devices increases, the probability of failure increasesdramatically. With the chance of one device failing in some way andeffective means of repairing or replacing currently unavailable, yieldrates have been low and the manufacturing costs high.

U.S. Pat. No. 5,252,916 (Swart) discloses a fluid-activated fixture forprinted circuit boards. An electrically conductive barrel 22 (alsoreferred to as an eyelet) is press fitted into each bore 20. Separatetest probes 24 are movably mounted in each of the barrels 22. A flexcircuit 30 is laminated to a bottom surface of the upper probe plate 16.Each barrel 22 has an outer flange that pierces a circuit trace andseats the flange to the circuit trace to form an electrical connection.The test probes 24 are movable axially in their respective barrelsfreely and under gravity. The test probes slide on the inside of thebarrels 22 for making sliding electrical contact. The barrels 22 pressfit into the support plate 16 make electrical contact with the flexiblecircuit 30. The first ends of the test probes 24 are supported by aflexible elastomeric diaphragm 42.

U.S. Pat. No. 4,118,090 (Del Mei) discloses a plurality of movableelectrically conductive contacts 10 slidably located in cylindricalapertures 14 in a locating element 16. The contacts 10 are each attachedto an electrically insulating elastomeric element 18 which has beenbonded to the contacts by molding the element 18 about the contacts 10.A retaining member 20 is provided on the opposite side of theelastomeric element 18 to the locating element and traps the elastomericelement between itself and the locating element.

WO 98/13695 discloses a connector apparatus in which an anisotropiccompliant conductive interposer 214 electrically couples contactelements 208 to contact pads 322 on an interface board 320. Stop rings312 retain the contact elements 208 in the guide plate 108. Theanisotropic interposer 214 is comprised of an elastomeric sheet 350 witha plurality of conductors 352. The interposer 214 serves as apass-through for electrical signals between the contact elements 208 andthe interface board 320.

U.S. Pat. No. 5,723,347 (Hirano et al.) discloses a probe structure witha plurality of conductive contacts formed on a film stretched across aplurality of cavities in a substrate. The cavities and the conductivecontacts are aligned to one another and both match the positions ofselected I/O pads on the device to be probed.

U.S. Pat. No. 5,412,329 (Jino et al.) discloses a probe card having asupporting plate, a flexible printed circuit base including a flexiblefilm base material supported by the supporting plate, circuits printedon the film base material being connected electrically to a tester,contracters connected electrically to the printed circuits and adaptedto be brought into contact with the pads in equally correspondingrelation, and a cushioning medium designed so as to back up a section inwhich the contactors are mounted. When the contactors are brought intocontact with the pads, individually, the cushioning medium undergoes anelastic deformation, so that the contact between the contactors and thepads is improved.

EP 0 310 302 discloses a test socket for testing chips and chips on tapewherein the test socket is formed on a heat resistant dielectric filmhaving contact pads and connector pads joined by metallic circuit tracesand which film is wrapped on a compliant pad. The connector end of thetape is joined to a circuit board by a conductive tape and maintained incontact by the compliant pad. A frame registers the chip with thecontact area of the tape.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to a method and apparatus forachieving a very fine pitch interconnect between a flexible circuitmember and another circuit member with extremely co-planar electricalcontacts that have a large range of compliance. The second circuitmember can be a printed circuit board, another flexible circuit, abare-die device, an integrated circuit device, an organic or inorganicsubstrate, a rigid circuit and virtually any other type of electricalcomponent.

The present invention is also directed to an electrical interconnectassembly comprising a flexible circuit member electrically coupled to anelectrical connector in accordance with the present invention. Thepresent electrical interconnect assembly can be used as a die-level testprobe, a wafer probe, a printed circuit probe, a connector for apackaged or unpackaged circuit device, a conventional connector, asemiconductor socket, and the like.

The present method includes preparing a plurality of through holesextending between a first surface and a second surface of a housing.Each of the through holes defines a central axis. A plurality ofelongated electrical contacts are positioned in at least some of thethrough holes and oriented along the central axis. The electricalcontacts have first ends that extend beyond the first surface. Theelectrical contacts are retained in the through holes by a variety oftechniques. The first ends of the electrical contacts are electricallycoupled to contact pads or terminals on a flexible circuit so that thesecond ends of the electrical contacts extend beyond the second surface.The second ends of the electrical contacts are then free to electricallycouple with a second circuit member. A resilient member controlsmovement of the electrical contacts along their respective central axeswithin the housing.

The step of retaining the electrical contacts in the through holes canbe achieved by interposing a compliant encapsulating material between aportion of the through holes and a portion of the electrical contacts,surrounding a portion of the electrical contacts with an encapsulatingmaterial along one of the surfaces of the housing, bonding the first endof the electrical contacts to the terminals on the flexible circuit,and/or positioning a compliant material along a surface of the flexiblecircuit opposite the terminals. A back-up member may optionally bepositioned behind the compliant material. In one embodiment, thecompliant encapsulant elastically bonds the electrical contacts to thehousing.

In one embodiment, the step of positioning the plurality of electricalcontacts includes applying a solder mask material or comparabledissolvable/removable material along the first surface. The solder maskmaterial and a portion of the electrical contacts extending above thefirst surface are planarized. When the solder mask is removed, theelectrical contacts have precisely formed end surfaces that extendsabove the first surface of the housing. The resilient member canoptionally be applied to the electrical contacts either beforeapplication of the solder mask or after removal of the solder mask.

The ends of the electrical contacts can be modified by a variety oftechniques, such as etching, grinding, abrasion, ablation or the like.The ends of the electrical contacts can also be modified to have a shapethat facilitates engagement with various structures on the flexiblecircuit member or the second circuit member. The second ends of theelectrical contacts can be configured to engage with another flexiblecircuit, a ribbon connector, a cable, a printed circuit board, a baredie device, a ball grid array, a land grid array, a plastic leaded chipcarrier, a pin grid array, a small outline integrated circuit, a dualin-line package, a quad flat package, a flip chip, a leadless chipcarrier, and a chip scale package.

The first ends of the electrical contacts are electrically coupled tothe flexible circuit bonding pads using a variety of techniques, such asa compressive force, solder, wedge bonding, conductive adhesives, solderpaste, ultrasonic bonding, wire bonding, or a combination thereof. Inone embodiment, the flexible circuit is bonded to the first surface ofthe housing with an adhesive.

The electrical connector in accordance with the present inventionincludes a housing with a plurality of through holes extending between afirst surface and a second surface. A plurality of elongated electricalcontacts are positioned in the through holes and oriented along thecentral axis. The first ends of the electrical contacts are electricallycoupled to the terminals on the flexible circuit. The second ends extendbeyond the second surface of the housing to couple electrically with thesecond circuit member. A resilient member controls movement of theelectrical contacts along their respective central axes. The resilientmember can be an encapsulating material interposed between a portion ofthe through hole and a portion of the electrical contacts, anencapsulating material surrounding a portion of the electrical contactsalong one of the surfaces of the housing, the flexible circuit bonded tothe contacts, a singulated terminal on the flexible circuit, and/or acompliant material positioned along a surface of the flexible circuitopposite the terminals.

The electrical contacts can be a multi-layered construction or ahomogenous material. The electrical contacts may have a cross-sectionalshape of circular, oval, polygonal, or rectangular. The electricalcontacts can have a pitch of less than about 0.4 millimeters andpreferably a pitch of less than about 0.2 millimeters.

The present invention is also directed to an electrical interconnectassembly comprising a flexible circuit bonded to the first ends of theelectrical contacts in the housing. A resilient member controls movementof the electrical contacts along their respective axes. The second endsof the electrical contacts are free to engage with a variety of secondcircuit members, or to operate as test probes for testing variouselectrical components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of an electrical interconnect inaccordance with the present invention.

FIG. 1A is a side sectional view of an alternate electrical interconnectin accordance with the present invention.

FIG. 1B is a side sectional view of another alternate electricalinterconnect in accordance with the present invention.

FIG. 2 is a side sectional view of a method of modifying the electricalinterconnect of FIG. 1.

FIG. 3 is a side sectional view of a method of modifying the electricalinterconnect of FIG. 2.

FIG. 4 is a side sectional view of an electrical contact modified inaccordance with the method of the present invention.

FIG. 5 is a side sectional view of an electrical contact modified inaccordance with an alternate method of the present invention.

FIG. 6 is a side sectional view of an electrical contact bonded to aflexible circuit in accordance with the present invention.

FIG. 7 is a side sectional view of an alternate method of bonding theflexible circuit to the electrical contact in accordance with thepresent invention.

FIG. 8 is a side sectional view of an alternate method of bonding theflexible circuit to the electrical contact in accordance with thepresent invention.

FIG. 9 is a side sectional view of an electrical interconnect bonded toa flexible circuit in accordance with the present invention.

FIG. 9A is a side sectional view of an alternate electrical interconnectbonded to a flexible circuit in accordance with the present invention.

FIG. 10 is a perspective view of an flexible circuit member inaccordance with the present invention.

FIG. 11 is a side sectional view of a singulated flexible circuit inaccordance with the present invention.

FIG. 11A is a non-singulated flexible circuit in accordance with thepresent invention.

FIG. 12 is side sectional view of an alternate electrical interconnectbonded to a flexible circuit member in accordance with the presentinvention.

FIG. 13 is a side sectional view of a flexible circuit bonded to anelectrical interconnect in accordance with the present invention.

FIG. 14 is a side sectional view of the electrical interconnect of FIG.13 in an engaged state.

FIG. 15 is a side sectional view of an alternate electrical interconnectbonded to a singulated flexible circuit in accordance with the presentinvention.

FIG. 15A is side sectional view of an alternate electrical interconnectin which the flexible circuit and encapsulating material are singulatedin accordance with the present invention.

FIG. 16 is a side sectional view of an electrical interconnect assemblyin accordance with the present invention engaged with a second circuitmember.

FIG. 17 is a side sectional schematic illustration of an electricalinterconnect assembly in which both surfaces of the flex circuit memberare used for forming electrical connections.

FIG. 18 is a side sectional view of two electrical interconnects inaccordance with the present invention in a stacked configuration.

FIG. 19 is a replaceable chip module coupled to a flexible circuitmember using the controlled compliance interconnect of the presentinvention.

FIG. 20 is a pair of replaceable chip modules in a stacked configurationcoupled by a flexible circuit member using the controlled complianceinterconnect of the present invention.

FIG. 21 is a side sectional view of an electrical interconnect bonded toa two-sided flexible circuit in accordance with the present invention.

FIG. 22 is a side sectional view of an electrical interconnect assemblyin accordance with the present invention.

FIG. 23 is a perspective view of an electrical interconnect coupled to adisplay in accordance with the present invention.

FIG. 24 is a schematic illustration of an electrical interconnect usedas a test probe in accordance with the present invention.

FIG. 25 is a perspective view of electrical interconnect used as a testprobe for wafer level devices in accordance with the present invention.

FIG. 26 is a side sectional view of a two-sided electrical interconnectin accordance with the present invention.

FIG. 27A is a side sectional view of an electrical interconnect assemblyin a disengaged configuration in accordance with the present invention.

FIG. 27B is a side sectional view of the electrical interconnectassembly of FIG. 27A in an engaged configuration in accordance with thepresent invention.

FIG. 28A is a side sectional view of an alternate electricalinterconnect assembly in a disengaged configuration in accordance withthe present invention.

FIG. 28B is a side sectional view of the electrical interconnectassembly of FIG. 28B in an engaged configuration in accordance with thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a side sectional view illustrating a step in the method ofmaking an electrical interconnect 30 in accordance with the presentinvention. Housing 32 has a plurality of through holes 34 that extendfrom a first surface 36 to a second surface 38. Each of the holes 34defines a central axis 40. Housing or interposer 32 may be constructedfrom a dielectric material, such as plastic, ceramic, metal with anon-conductive coating. The holes can be formed by a variety oftechniques, such as molding, laser drilling, or mechanical drilling. Theholes 34 can be arranged in a variety of configuration, including one ortwo-dimensional arrays. The housing 32 may optionally include a toolinghole 42 to facilitate handling and alignment with other components.

A plurality of rigid or semi-rigid electrical contacts 44 are positionedin some or all of the holes 34. The electrical contacts 44 may bepositioned in the holes 34 by a variety of techniques, such as manualassembly, vibratory assembly, or robotic assembly. In the illustratedembodiment, the electrical contacts 44 are maintained in their desiredlocation by a height fixture 46. Upper ends 62 of the electricalcontacts 44 may exhibit height differences based upon the manufacturingtolerances and constancy of the manufacturing process.

The electrical contacts may be a variety of materials, such as wire,rod, formed strips, or turned or machined members. The electricalcontacts can have a cross-sectional shape that is circular, oval,polygonal, or the like. The electrical contacts can be made from avariety of materials, such as gold, copper, copper alloy, palanae, ornickel. The electrical contacts 44 are typically cut or formed into ageneral length, which reduces cost and handling difficulties. Theelectrical contacts are modified during subsequent processing steps toachieve the necessary precision, such as planarity and tip shape. Inorder to achieve a fine pitch without shorting, the electrical contactmust typically be straight to within about 0.25 millimeters and be rigidor semi-rigid in construction. The electrical contacts 44, however, mayhave a different cross section at various locations along their entirelength (see FIG. 1A).

In the embodiment illustrated in FIG. 1, a compliant encapsulatingmaterial 50 is applied to the first surface 36. The compliantencapsulating material 50 surrounds the electrical contacts 44 and bondsto the first surface 36. In the illustrated embodiment, the complaintencapsulating material penetrates at least part way into the holes 34.In an alternate embodiment, the encapsulating material 50 remainsgenerally on the surface 36. The compliant encapsulating material 50permits the electrical contacts 44 to move elastically along the centralaxis 40, while retaining them in the housing 32. Suitable compliantencapsulating materials include Sylgard® available from Dow CorningSilicone of Midland, Mich., and MasterSyl 713, available from MasterBond Silicone of Hackensack, N.J.

FIG. 2 illustrates another step in the method of forming the electricalinterconnect 30 in accordance with the present invention. The firstsurface 36 and/or the second surface 38 are flooded with one or moreretention materials 60 that will assist in the farther processing steps.The retention material 60 can be a compliant encapsulant or a materialthat cures solid, such as a solder mask. Once the retention material 60has cured, the electrical contacts 44 are rigidly held to the housing 32so that the fixture 46 can be removed. The material retention 60 canoptionally be applied to the second surface 38. In an alternateembodiment, the compliant encapsulating material 50 is omitted and theretention material 60 is applied directly to the first surface 36.

FIG. 3 is a side sectional view showing a subsequent step in theprocessing of the electrical interconnect 30 in accordance with thepresent invention. The retention material 60 retains the electricalcontacts 44 in the housing 32 so that ends 62, 64 can be processedwithout flexural displacement or damage. The assembly is subjected to aprecision grinding operation, which results in very flat ends 62, 64 onthe electrical contacts 44, typically within about 0.0005 inches. Thegrinding operation can be performed on both sides at the same time usinga lapping or double grinding process. In an alternate embodiment, onlyone surface 36, 38 of the electrical interconnect 30 is subject to theplanarization operation. The retention material 60 is then dissolvedfrom the electrical interconnect 30 to expose the first and second ends62, 64, of the electrical contacts 44 (see FIG. 9). In an alternateembodiment, the first and/or second ends 62, 64 of the electricalcontacts are subject to further processing prior to removal of thematerial 60.

FIG. 1A illustrates an alternate embodiment method of making anelectrical interconnect 30′ in accordance with the present invention.Upper ends 62′ of the electrical contacts 44′ have a cross sectionalportion 61′ that is larger than the cross sectional area of the holes34′ that engages with the first surface 36′. Consequently, theelectrical contacts 44′ are always oriented in the same direction in thehousing 32′, even when positioned using automated processes such asvibratory assembly. The cross sectional portion 61′ also makes thefixture 46 of FIG. 1 unnecessary. The electrical interconnect 30′ maysubsequently processed as discussed herein, such as application of acompliant encapsulating material 50′. Alternatively, the upper ends 62′can be deformed during a subsequent processing step.

FIG. 1B illustrates another alternate embodiment method of making anelectrical interconnect 30″ in accordance with the present invention. Inthe illustrated embodiment the electrical contacts 44″ are generally ofthe same length. Fixture 46″ has support surfaces at various levelsrelative to second surface 38″ of housing 32″. Consequently, theelectrical contacts 44″ are maintained in the holes 34″ in a stepconfiguration. The electrical interconnect 30″ may be subsequentlyprocessed as discussed herein, such as application of a compliantencapsulating material 50″. In one embodiment, a retention material 60(see FIG. 2) is applied to the first surface 36″. The ends 62″ of theelectrical contacts 44″ are planarized, such as is illustrated in FIG.3. The ends 64″ extending beyond the surface 38″, however, are notplanarized and retain the step configuration.

Depending on the material of the electrical contacts 44 and the desiredfunction, the planar ends 62, 64 may exhibit different properties. Ifthe electrical contacts are made of a copper base metal or alloy andplated with a barrier layer and a gold layer, the grinding process willremove the nickel and gold from the tips, exposing base metal that willoxidize. If the electrical contact 44 is a material such as gold orpalanae, corrosion is minimized. The ends 62, 64 can be tailored forspecific applications, such that the first end 62 may have a differentstructure or shape than the second end 64.

Depending on the type of terminal the electrical contact 44 is intendedto interface with, it may be desirable to abrasively process the tipssuch that the ends 62, 64 are still essentially planar but have asurface which is more irregular than that left by the grinding process.This abrasive processing can also be of a cleaning nature to remove anyoxides formed between process steps. FIG. 4 illustrates one embodimentof an ends 62, 64 of an electrical contact 44 that has been subject toan abrasive blast operation to provide a correspondingly rough surface.

FIG. 5 illustrates an alternate ends 62, 64 of an electrical contact 44that has been subject to an etching process. In the illustratedembodiment, the electrical contact 44 is constructed from a copper alloycore 70, an intermediate nickel layer 72 and an outer gold layer 74.When subjected to an etching solution, only the copper alloy 70 isremoved. In the illustrated embodiment, the ends 62, 64 has a generallyconcave tip shape, where the outer walls 72, 74 extend beyond thepost-processed base metal 70. The ends 62, 64 can then be processed todeposit another barrier to prevent contamination by oxides, such as agold layer (see FIG. 6). In some instances, it may be acceptable toleave the base metal 70 untreated.

The generally concave shape of the ends 62, 64 can provide severaldesired functional properties, such as contacting a solder, gold, orother deposits in a generally mating fashion, without excessivelydeforming the deposits. Additionally, the protruding outer wall 72, 74provides a slight wiping action during mating with the correspondingcomponent. The outer walls 72, 74 form a tubular structure thatincreases the pressure per unit area when compressively engaged with amating electrical circuit member. Finally, the concave shape of the ends62, 64 provides a reservoir for contamination on the terminal of themating circuit member, while the relatively hard outer layer 72, 74minimize deformation of the tip 62, 64. The etching process may beperformed either before or after removal of the material 60.

FIG. 6 is a side sectional view of a flexible circuit member 80 beingbonded to a electrical contact 82 in accordance with the presentinvention. The electrical contact 82 includes a barrier layer 84 alongthe ends 62, 64. In the illustrated embodiment, the terminals 86 on theflexible circuit member 80 include a ball structure 88 having a shapecorresponding to the ends 62, 64 of the electrical contact 82. The ballstructure 88 can be constructed from gold, solder, or a conductiveadhesive. The ball structure 88 is aligned to each correspondingelectrical contact ends 62, 64 and ultrasonically bonded. Alternatively,the ball structure 88 can be a solder ball or deposit, which can then bereflown to attach each electrical contact member 82. Several isotropicand anisotropic conductive adhesives are available to achieve similarresults. In another embodiment, the ball structure 88 can beelectrically coupled to the ends 62, 64 by a compressive force.

FIG. 7 is a side sectional view of an alternate electrical contact 90 inaccordance with the present invention. A barrier layer 92, such as gold,is deposited on the generally planar ends 62, 64 of the electricalcontact 90. The ball structure 88 of the flexible circuit member 80 isthen bonded to the barrier layer 92. FIG. 8 is a side sectional view ofa high density, flexible circuit member 100 being bonded to theelectrical contact 90 using a wire bonding technique.

FIG. 9 is a side sectional view of an electrical interconnect 110electrically coupled to bonding pads 113 on a flexible circuit member112 in accordance with the present invention. In the illustratedembodiment, the resilient encapsulating material 114 retains theelectrical contacts 116 within the housing 118, but permits movementalong the central axes. The first ends 120 of the electrical contacts116 may be electrically coupled with the flexible circuit 112 using avariety of techniques discussed herein, such as applying a compressiveforce, solder, wedge bonding, conductive adhesives, ultrasonic bondingand wire bonding. The second ends 122 of the electrical contacts 116extend beyond the second surface 124 of the housing 118 to coupleelectrically with a second circuit member (see FIG. 16).

FIG. 9A illustrates an alternate embodiment of an electricalinterconnect 110′ electrically coupled a flexible circuit member 112′ inaccordance with the present invention. The flexible circuit member 112′has a series of pass through openings. The flexible circuit member 112′is aligned to the electrical contacts 16′ such that the pass thoughopenings are located directly on each electrical contact end 120′ in thearray. A gold ball bonder can then be used to bond the flexible circuitmember 112′ to the ends 120′ of the electrical contacts 116′, where thegold balls 115′ extend to an exposed conductive layer in the flexiblecircuit member 112′.

Once the flexible circuit member 112 is attached, several options can beemployed to increase the function of the electrical interconnect 110.These features, discussed in detail below, provide a relatively largerange of compliance of the electrical contacts 116, complimented by theextreme co-planarity of the electrical contact ends 122. The nature ofthe flexible circuit 112 allows fine pitch interconnect and signalescape routing, but also inherently provides a mechanism for compliance.One option is to allow the flexing nature of the flexible circuit member112 to provide compliance as the lower ends 122 are compressed. Thesemi-rigid or rigid nature of the electrical contacts 116 will transmitthe incident force to the flexible circuit member 112 and cause flexureat the area around the bond sites 113. The flexible circuit member 112can be left separate from the housing 118 to allow a free range ofmovement or the flexible circuit 112 can be selectively bonded to thehousing 118 to restrict movement if desired.

FIG. 10 is a perspective view of a flexible circuit member 140 inaccordance with the present invention. The flexible circuit member 140includes a series of electrical traces 142 deposited on a polymericsheet 144 and terminating at a plurality of terminals or terminals 146.As used herein terminal refers to an electrical contact location orcontact pad. In the illustrated embodiment, the terminals 146 include asingulation 148. Singulation refers to a partial separation of theterminal from the sheet that does not disrupt the electrical integrityof the conductive trace. The partial separation can be a perforation inthe polymeric sheet 144. Alternatively, singulation may include athinning or point of weakness of the sheet material along the edge of,or directly behind, the terminal. In the illustrated embodiment,singulating the flexible circuit member 140 near or around the terminals146 releases or separates the terminal from the sheeting 144, whilemaintaining the interconnecting circuit traces 142. The singulations canbe formed at the time of manufacture or the sheeting 144 can besubsequently patterned by stamping, cutting or a variety of othertechniques. In one embodiment, a laser system, such as Excimer, CO2, orYAG, creates the singulation 148. This structure is advantageous inseveral ways, where the force of movement is greatly reduced since theflexible circuit member 140 is no longer a continuous membrane, but aseries of flaps or bond sites with a living hinge and bonded contact.

In the illustrated embodiment, the singulation 148 is a slit surroundinga portion of the terminal 146. The slit may be located adjacent to theperimeter of the terminal 146 or offset therefrom. The singulation 148may be formed to serve as the resilient member for controlling movementof the electrical contacts along their respective central axes. Thesingulated terminal 146 can be left free from the housing or it can beselectively bonded such that the hinged portion is allowed to movefreely within a given range. The singulated flexible circuit member 140can also be encapsulated or mated with a compliant sheet to control theamount of force, the range of motion, or assist with creating a moreevenly distributed force vs. deflection profile across the array (seeFIG. 11).

FIG. 11 is a side sectional view of an electrical contact 150electrically coupled to a flexible circuit member 152. The terminal 154of the flexible circuit member 152 has been singulated at a location156. A compliant encapsulating material 158 has been deposited on thesurface of the flexible circuit member 152 opposite the electricalcontact 150. Alternatively, the flexible circuit member 152 can be matedwith a compliant sheet of material to provide controlled force andcompliance. The additional layer of compliant encapsulant or sheetingcan also be precision ground to provide uniform thickness and complianceacross the array. In the illustrated embodiment, movement of theelectrical contact 150 along the central axis 162 is controlled by thecompliant encapsulant 166 deposited around the electrical contact 150,the resiliency of the flexible circuit member 152, and the resiliency ofthe compliant encapsulant 158. These components are engineered toprovide a desired level of compliance to the electrical contact 150within the housing 166.

In the illustrated embodiment, a portion of the compliant encapsulatingmaterial 160 has seeped through the singulation 156. The liquid natureof the uncured encapsulant can be taken advantage of by applying orinjecting it into the singulation gap 157 under a slight vacuumcondition in the region 159 between the flexible circuit member 152 andthe encapsulant 166. The material 158 is drawn into the singulation gap157. The encapsulated gap 157 supports and controls the motion of theterminal 154. This control can minimize the flexural stress and fatigueof the singulated terminal 154, increasing mechanical performance andlife. In an alternate embodiment, the compliant sheet or encapsulant 158can be applied prior to singulation of the flexible circuit member 152,such that the living hinge mechanism is a laminate or composite of thecompliant encapsulant 158 and the flexible circuit member 152.

FIG. 11A is a side sectional view of an electrical contact 150Aelectrically coupled to a flexible circuit member 152A, withoutsingulation of the terminals 154A. A vacuum is applied in the region159A between the flexible circuit member 152A and the encapsulant 166Aprior to applying the complaint encapsulating material 168A. The vacuumdraws the flexible circuit member 152A down at the bond sites 154A andforms a dimple 155A over the first end 157A of the electrical contact150A. Application of the complaint encapsulant 168A fills the dimples155A, and when the vacuum is removed, the flexible circuit member 152Awill have a different shape and a preload caused by the material 168A inthe dimple 155A biasing the electrical contact 150A downward. A layer ofcompliant material 158A may optionally be applied to the outer surfaceof the flexible circuit member 152A.

FIG. 12 is a side sectional view of an alternate electrical interconnect170 in accordance with the present invention. The electrical contacts172 have been prepared using the techniques discussed above, but nocompliant encapsulating material was applied. Height fixture 174 retainsthe electrical contacts 172 at the desired position within the housing176. A flexible circuit member 178 is bonded to the first ends 180 ofthe electrical contacts 172, using any of the techniques discussedabove. Once the electrical contacts 172 are bonded to the flexiblecircuit member 178, the fixture 174 can be removed. The electricalcontacts 172 are then suspended within the housing 176 by the flexiblecircuit member 178. Compliance is provided by the resiliency of theflexible circuit member 178. In one embodiment, the flexible circuitmember is bonded to the housing 176. Other compliant members mayoptionally be added to the electrical interconnect 170.

FIG. 13 is a side sectional view showing one embodiment of an electricalinterconnect 190 in an disengaged configuration. The flexible circuitmember 192 is bonded to the electrical contact 194 as discussed herein.No encapsulating material is provided between the electrical contact 194and housing 196. The electrical contact is suspended in the housing 196by the flexible circuit member 192. The flexible circuit member 192 isoptionally bonded to housing 196 with an adhesive layer 202. Theflexible circuit member 192 is optionally singulated at the location 198to provide a flexure point 200.

FIG. 14 is a side sectional view of the electrical interconnect 190 ofFIG. 13 in an engaged configuration. The electrical contact 194 has beendisplaced in the direction 204, causing the flexible circuit member 192to flex at the flexure point 200. In the embodiment illustrated in FIGS.13 and 14, the sole resilient member is the flexible circuit 192. Inalternate embodiments, a compliant encapsulating material may bepositioned along the rear surface 206 of the flexible circuit member 192(see FIGS. 11A, 11B and 15).

FIG. 15 is a side sectional view of an electrical interconnect 210 inwhich the resiliency of a singulated, flexible circuit member 192 issupplemented by a compliant encapsulating material 212 positioned alongthe rear surface 214 of the flexible circuit 192 and a compliantencapsulating material 222 deposited between the flexible circuit 192and the housing 196. The compliant encapsulating material 212 may bedeposited as a liquid or positioned in sheet form, as discussed above.An adhesive layer 216 may optionally be provided for retaining theflexible circuit member 192 to the housing 196.

FIG. 15A is a side sectional view of an electrical interconnect 210A inwhich both the flexible circuit member 192A and the compliantencapsulating material 212A are singulated at a location 218A. Thecompliant encapsulating material 212A may be deposited in liquid form orpositioned as a sheet form, as discussed above. An adhesive layer 216Amay optionally be provided for retaining the flexible circuit member192A to the housing 196A. The flexible circuit member 192A may besingulated prior to application of the encapsulating material 212A, orsimultaneously therewith. A back-up member 220A may optionally belocated behind the compliant material 192A to provide additionalsupport. The back-up member 220A may be part of a larger assembly usingthe present electrical interconnect 210A.

FIG. 16 is a side sectional view of an electrical interconnect assembly230 in accordance with the present invention. First ends 232 of theelectrical contacts 234 are electrically coupled to a flexible circuit236, using any of the techniques described herein. A compliantencapsulant or sheet material 238 is deposited on the rear surface ofthe flexible circuit 236. The second ends 240 of the electrical contacts234 extend beyond the second surface 242 of the housing 244 to coupleelectrically with terminals 246 on a second circuit member 248. Theterminals 246 may be a variety of structures such as, for example, aball grid array, a land grid array, a pin grid array, contact points ona bare die device, etc. Similarly, the second ends 240 of the electricalcontacts 234 can be a variety of shapes as discussed herein. The secondcircuit member 248 can be a printed circuit board, another flexiblecircuit, a ribbon cable, a bare die device, an integrated circuitdevice, organic or inorganic substrates, a rigid circuit or a variety ofother electrical components.

In the illustrated embodiment, the electrical interconnect assembly 230is releasably coupled to the second circuit member 248 by a compressiveforce 249. The compliance of the flexible circuit member 236, complaintmaterial 238 and encapsulating material between the electrical contacts234 and the housing 244, if any, provides the electrical contacts 234with a large range of compliance along the central axes 247.Consequently, a stable electrical connection can be formed withoutpermanently bonding the second ends 240 to the terminals 246. Theelectrical interconnect assembly 230 can serve as a die level testprobe, a wafer probe, a printed circuit probe, or a variety of othertest circuits. The various complaint members in the assembly 230 permitit to be oriented in any direction without interfering with itsfunctionality.

The nature of the flexible circuit member 236 allows for a high densityrouting to external circuitry or electronics. The present electricalinterconnection methodology can be extended to the distal end of theflexible circuit member 236 as well, to achieve a high performanceconnection where previous methods relied on cabling, spring probes, ormasses of bundled wires.

FIG. 17 is a side sectional schematic illustration of an electricalinterconnect assembly 280 in which both surfaces of the flex circuitmember 282 can be used for forming electrical connections. The flexcircuit member 282 is bonded to housing 284 by an adhesive 286.Singulation 288 is formed in the flex circuit members 282 around trace290. Electrical contact 292 is positioned to be compressively engagedwith the trace 290 between circuit member 294 and controlled compliancelayer 296 (see generally FIGS. 15A and 15). Solder balls 298electrically coupled with one or more traces are located on the oppositeside of the flex circuit member 282 for engagement with circuit membersor other electrical interconnect assemblies.

FIG. 18 is a schematic illustration of two electrical interconnectassemblies 250, 252 arranged in a stacked configuration in accordancewith the present invention. First ends 254 of the electrical contacts256 are electrically coupled with a flexible circuit member 258. Theflexible circuit member 258 is folded around a compliant layer 260 sothat first ends 262 of electrical contacts 264 in the electricalinterconnect assembly 252 are also electrically coupled to the flexiblecircuit member 258. Second ends 266 of the electrical contacts 256 areelectrically coupled with a second circuit member 268. Second ends 270of the electrical contacts 264 are electrically coupled with circuitmember 272. An alignment member 274 is optional provided on theinterconnect assembly 252 to position the circuit member 272 relative tothe electrical contacts 264. The electrical interconnect assemblies 250,252 of FIG. 17 permit two circuit devices 268, 272 to be arranged in astacked configuration.

FIG. 19 illustrates a replaceable chip module 310 coupled to a flexiblecircuit member 312 using the controlled compliance interconnect of thepresent invention. Housing 314 has a plurality of device sites 316, 318for receiving circuit members, such as an array of integrated circuitdevices. The device sites 316, 318 are recesses that each contain anarray of electrical contacts, such as discussed herein. The housing 314is retained against the flexible circuit member 312 using any of themethods discussed herein, such as mechanical fasteners, adhesives,secondary fixtures, etc. A controlled compliance layer 320 is optionallylocated behind the flexible circuit member 312. A stiffener 322 isoptionally located behind the controlled compliance layer 320. Theflexible circuit member 312 can be formed with or without singulation.In the illustrated embodiment, the flexible circuit member has a seriesof terminals 326 for electrically coupling the replaceable chip module310 with another circuit member. Alignment holes 324 are optionallyprovided on the housing 314 for receiving a cover (not shown) thatretains circuit members in the device sites 316, 318 and provides acompressive force.

The housing 314 allows for a great deal of configuration flexibility,such that it can be populated, upgraded, enhanced, or modified simply byremoving, replacing, or adding individual circuit members or devices.The replaceable chip module 310 of FIG. 19 is suited as a test fixturefor evaluating circuit members. Conventional test or load boards used asthe interface for testing electrical devices can be greatly simplifiedor in some cases completely eliminated along with the supportingmechanical and electrical support or interface structure. Thereplaceable chip module technology disclosed in U.S. patent Ser. No.08/955,563, entitled Replaceable Chip Module, is suitable for use in thepresent invention.

FIG. 20 is a side sectional schematic illustration of a pair ofreplaceable chip module 330, 332 using the controlled complianceinterconnect of the present invention in a stacked configuration,coupled together by a flexible circuit member 334. The flexible circuitmember 334 is folded around a compliant layer 336, such as isillustrated in FIG. 18. The assembly 338 of the folded flexible circuitmember 334 and compliant layer 336 is retained in a cavity 340 formedbetween the first replaceable chip module 330 and the second replaceablechip module 332. The various interfaces 341 between the flexible circuitmember 334 and the electrical contacts 342, 344 of the respectivereplaceable chip modules 330, 332 can be formed using any of thetechniques disclosed herein. For example, the electrical contacts 342are illustrated as coupling with a ball grid array on circuit member346. Electrical contacts 344 can couple with another replaceable chipmodule, another flexible circuit members or various circuit members. Analignment structure 346 may optionally be located on the secondreplaceable chip module 332 for positioning circuit members.

FIG. 21 is a side sectional view of an electrical interconnect 400 inaccordance with the present invention. Housing 402 includes an array ofholes 404 each having a step 406. Electrical contacts 408 include ashoulder 410 adapted to engage with the step 406. Consequently, theelectrical contacts 408 can move in the holes 404 along the centralaccess 412 until the shoulders 410 engage with the steps 406. First ends414 of the electrical contacts 408 extend above surface 416 of housing402.

Second ends 418 of the electrical contacts 408 are electrically coupledto contact pads on flexible circuit member 420 using any of the methodsdiscussed herein. The flexible circuit member optional includessingulations 422 adjacent to one or more of the electrical contacts 408.A compliant material 424 is positioned on the opposite side of theflexible circuit member 420 behind the second ends 418 of each of theelectrical contacts 408. The compliant material 424 biases theelectrical contacts 408 in the direction 426.

The second surface 430 of the flexible circuit member 420 optionallyincludes a series of solder balls 432 electrically coupled to traces onthe flexible circuit member 430. Solder paste 434 may optionally beapplied to the solder balls 432.

FIG. 22 illustrates an electrical interconnect assembly 440 utilizingthe electrical interconnect 400 of FIG. 21. The electrical interconnect400 is located in an alignment device 442 positioned on a first circuitmember 444. Flexible circuit member 420 (see FIG. 21) extends beyond thealignment device 442 to connect with another circuit member. The solderballs 432 (see FIG. 21) electrically couple the flexible circuit member420 with contact pads on the circuit member 444. In the illustratedembodiment, the circuit member 444 is a printed circuit board oradapter. The circuit member 444 will typically include an additionalconnector, such as an edge card connector or the socket 7 compatible BGAadapter 446 illustrated in FIG. 22.

A second circuit member 450 is compressively engaged with the electricalinterconnect 400. Alignment device 442 ensures that the contact pads onthe second circuit member 450 align with the electrical contacts 408 onthe electrical interconnect 400. Compliant material 424 biases theelectrical contacts 408 into engagement with the contact pads on thesecond circuit member 450. In the illustrated embodiment, the secondcircuit member 450 is a land grid array (LGA) device. A heat sink 452 isoptionally provided to retain the second circuit member 450 incompressive engagement with the electrical interconnect 400.

FIG. 23 illustrates an alternate electrical interconnect 460 inaccordance with the present invention. Flexible circuit member 462 iselectrically coupled to an array of pins (see generally FIG. 21)retained in housing 464. The flexible circuit member 462 may optionallyinclude an edge card connector 466. The pins in the electricalinterconnect 460 are compressively engaged with a land grid array device468 on circuit member 470. In the illustrated embodiment, circuit member470 is a display device. The embodiment illustrated in FIG. 23 isparticularly suited for use in lap top computers where the flexiblecircuit member 462 permits the display 470 to be hinged to the chassisof the computer.

FIG. 24 is a schematic illustration of an electrical interconnect 480used as a probe module 482 in accordance with the present invention.Electrical contacts 484 are electrically coupled to flexible circuit486. Compliant material 488 supported by back-up member 494 biases theelectrical contacts 484 within the probe housing 490 towards a firstcircuit member 492. The first circuit member 492 can be a variety ofelectrical devices or a wafer containing a plurality of electricaldevices (see FIG. 25).

The flexible circuit 486 can extend to one or more circuit members. Inthe illustrated embodiment, the flexible circuit member 486 includes afirst branch 496. The branch 496 includes a series of edge card pads(not shown) and a stiffening member 498 to form an edge card connector500.

Second branch 502 extends to another electrical interconnect 504 thatincludes a compliant material 506, a backup member 508, and a series ofelectrical contacts 510 in a housing 512. The electrical interconnect504 can be used to interface the probe module 482 to another circuitmember 514, such as a printed circuit board.

The tester 516 illustrated in FIG. 24 is completely modular. Any of thecomponents can be easily replaced to facilitate testing of a widevariety of circuit members 492. For example, a different probe module482 can be supplied so that the array of electrical contacts 482correspond with the contact pads on the circuit member 492.Alternatively, the electrical interconnect 504 can be easily attached toa different circuit member 514 for performing different tests.

FIG. 25 illustrates a system 520 for conducting full function testing atthe wafer level. Electrical interconnect 522 includes a module holder524 with a plurality of recesses 526. Each recess 526 is adapted toreceive a probe module, such as illustrated in FIG. 24. Each of theprobe modules 528 includes a flexible circuit 530 that can beelectrically coupled with one or more other circuit members for purposesof performing the testing.

Wafer 532 includes a plurality of electrical devices 534. The array ofrecesses on the module holder 524 correspond to the array of electricaldevices 534 on the wafer 532. The electrical interconnect 522 is placedover the wafer 532 so that the electrical contacts (see FIG. 24) of theprobe modules 528 electrically couple with contact pads on theelectrical devices 534. In one embodiment, the system 520 permits fullspeed testing of the electrical devices 534 at the wafer level.

FIG. 26 is a schematic illustration of an alternate electricalinterconnect 550 in accordance with the present invention. Flexiblecircuit member 552 electrically couples upper electrical contacts 554and lower electrical contacts 556. Elastomer 558 is positioned to biaselectrical contacts 554 upward in the direction 560. Upper housing 562includes a recess 564 for receiving a variety of circuit members.Elastomer 566 biases lower electrical contacts 556 retained in the lowerhousing 568 in the direction 570 for coupling with another circuitmember. In the embodiment illustrated in FIG. 26, the upper housing 562is a separate component from the lower housing 568.

FIG. 27A is a schematic illustration of another electrical interconnect580 in the disengaged configuration in accordance with the presentinvention. Substrate 582 supports a flexible circuit member 584 having aplurality of BGA contact pads 586. Electrical contacts 588 areelectrically coupled to the opposite side of the flexible circuit member584. Compliant member 590 is located behind each of the electricalcontacts 588. Gaps 592 in the compliant member 590 permit solder balls594 of a BGA device 596 to electrically couple with the BGA contact pads586 on the flexible circuit member 584.

FIG. 27B illustrates the electrical interconnect 580 of FIG. 27A in theengaged configuration. The electrical interconnect 580 is compressedbetween the BGA device 596 and a second circuit member, such as aprinted circuit board 598. The contact pads 600 on the printed circuitboard 598 bias the electrical contacts 588 toward the BGA device 596.The compliant material counteracts this bias on the electrical contacts588. Singulations 602 in the flexible circuit member 584 facilitatemovement of the electrical contacts 588 within the substrate 582. Solderballs 594 electrically couple with BGA contact pads 586 on the flexiblecircuit member 584.

FIG. 28A illustrates an electrical interconnect 620 substantially asshown in FIGS. 27A, except that the compliant material 622 includes aclearance opening or recess 624 immediately behind the electricalcontact 626.

In the engaged configuration illustrated in FIG. 27B, the electricalcontacts 626 are biased toward the printed circuit board 628 only by theelastomeric properties of the flexible circuit member 628. In analternate embodiment, the clearance opening 624 has a size that permitsthe electrical contact 626 to be supported substantially by the flexiblecircuit member 628 only for a portion of their travel. After an initialamount of travel by the electrical contact 626, the flexible circuitmember 628 engages with the compliant material 622. Thereafter, furtherdisplacement of the electrical contact 626 is biased towards the printedcircuit board 628 by a combination of the elastomeric properties of theflexible circuit member 628 and the compliant material 622.

Patents and patent applications disclosed herein, including those citedin the background of the invention, are hereby incorporated byreference. Other embodiments of the invention are possible. It is to beunderstood that the above description is intended to be illustrative,and not restrictive. Many other embodiments will be apparent to those ofskill in the art upon reviewing the above description. The scope of theinvention should, therefore, be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled.

What is claimed is:
 1. An electrical connector for electricallyinteconnecting terminals on a flexible circuit member with terminals ona second circuit member, the electrical connector comprising: a firsthousing having a plurality of through holes extending between a firstsurface and a second surface, each of the through holes defining acentral axis; a plurality of elongated electrical contact memberspositioned in at least a portion of the through holes and oriented alongthe central axes, the electrical contact members having first endsextending above the first surface adapted to couple electrically withthe terminals on the flexible circuit member, and second ends extendingabove the second surface to couple electrically with the second circuitmember; a resilient member comprising a compliant encapsulating materialinterposed between a portion of the through holes and a portion of theelectrical contact members to control movement of the electrical contactmembers along their respective central axes; and a compliant materialpositioned along a surface of the flexible circuit member opposite atleast one of the terminals of the flexible circuit member.
 2. Theelectrical connector of claim 1 wherein first ends of the electricalcontact members are attached to the terminals on the flexible circuitmember.
 3. The electrical connector of claim 1 wherein at least one ofthe terminals on the flexible circuit member comprises a singulatedterminal.
 4. The electrical connector of claim 1 wherein the complaintmaterial positioned along the opposite surface of the flexible circuitmember comprises a sheet material.
 5. The electrical connector of claim1 wherein the complaint material positioned along the opposite surfaceof the flexible circuit member is discontinuous.
 6. The electricalconnector of claim 1 wherein the second surface of the housing includesat least one device site corresponding to the second circuit member. 7.The electrical connector of claim 1 wherein the second ends of theelectrical contact members have a shape that corresponds to a shape ofthe terminals on the second circuit member.
 8. The electrical connectorof claim 1 wherein the second ends of the electrical contact members arecapable of engaging with a connector member selected from the groupconsisting of a flexible circuit, a ribbon connector, a cable, a printedcircuit board, a ball grid array (BGA), a land grid array (LGA), aplastic leaded chip carrier (PLCC), a pin grid array (PGA), a smalloutline integrated circuit (SOIC), a dual in-line package (DIP), a quadflat package (QFP), a leadless chip carrier (LCC), a chip scale package(CSP), or packaged or unpackaged integrated circuits.
 9. The electricalconnector of claim 1 wherein the electrical contact members are one of ahomogeneous material or a multi-layered construction.
 10. The electricalconnector of claim 1 wherein the electrical contact members have across-sectional shape selected from one of circular, oval, polygonal,and rectangular.
 11. The electrical connector of claim 1 wherein aportion of the flexible circuit member is bonded to the first surface ofthe housing.
 12. The electrical connector of claim 1 wherein theelectrical contact members are electrically coupled to the flex circuitusing one or more of a compressive force, solder, a wedge bond, aconductive adhesive, an ultrasonic bond and a wire bond.
 13. Theelectrical connector of claim 1 wherein the second ends of at least twoof the electrical contact members extend beyond the second surface ofthe housing by a different amount.
 14. The electrical connector of claim1 wherein electrical contact members have a larger cross sectionproximate the first end than at the second end.
 15. The electricalconnector of claim 1 wherein the plurality of through holes are arrangedin a two-dimensional array.
 16. The electrical connector of claim 1wherein the resilient member comprises a compliant encapsulating memberelastically bonding the electrical contact members to the housing. 17.The electrical connector of claim 1 wherein the second ends of theelectrical contact members comprises one or more of die level testprobes, wafer probes, and printed circuit board probes.
 18. Theelectrical connector of claim 1 comprising: a second housing having aplurality of through boles extending between a fist surface and a secondsurface, each of the through holes defining a central axis; a pluralityof elongated electrical contact members positioned in at least a portionof the through holes and oriented along the central axes, the electricalcontact members having first ends extending above the first surfaceadapted to couple electrically with the terminals on the flexiblecircuit member, and second ends extending above the second surface tocouple electrically with a third circuit member.
 19. The electricalconnector of claim 18 wherein the first surface of the first housing ispositioned opposite the first surface of the second housing.
 20. Theelectrical connector of claim 18 wherein the first housing and thesecond housing are arranged in a stacked configuration.
 21. Anelectrical connector comprising: a flexible circuit member having aplurality of terminals; a first housing having a plurality of throughholes extending between a first surface and a second surface, each ofthe through holes defining a central axis; a plurality of elongatedelectrical contact members positioned in at least a portion of thethrough holes and oriented alone the central axes, the electricalcontact members having first ends extending above the first surfaceadapted to couple electrically with the terminals on the flexiblecircuit member, and second ends extending above the second surfaceadapted to couple electrically with a second circuit member; a resilientmember comprising a compliant encapsulating material interposed betweena portion of the through holes and a portion of the electrical contactmembers to control movement of the electrical contact members alongtheir respective central axes; and a compliant material positioned alonga surface of the flexible circuit member opposite at least one of theterminals of the flexible circuit member.
 22. An electrical connectorfor electrically interconnecting terminals on a flexible circuit memberwith terminals on a second circuit member, the electrical connectorcomprising: a housing having a plurality of through holes extendingbetween a first surface and a second surface, each of the through holesdefining a central axis; a plurality of elongated electrical contactmembers positioned in at least some of the through holes and orientedalong the central axes, the electrical contact members having first endsextending above the first surface that are fixedly bonded to, andelectrically coupled with, the terminals on the flexible circuit member,the flexible circuit member controlling movement of the electricalcontact members along their respective central axes, and second endsextending above the second surface to couple electrically with thesecond circuit member; and a compliant encapsulating materialelastically bonding the electrical contact members to the housing. 23.The electrical connector of claim 22 wherein a portion of the compliantencapsulating material is located between the electrical contact membersand the holes in the housing.
 24. The electrical connector of claim 22wherein at least one of the terminals on the flexible circuit membercomprises a singulated terminal.
 25. The electrical connector of claim22 comprising a compliant material positioned along a surface of theflexible circuit member opposite at least one of the terminals of theflexible circuit member.
 26. The electrical connector of claim 25wherein the complaint material comprises a sheet material.
 27. Theelectrical connector of claim 25 wherein the complaint material isdiscontinuous.
 28. The electrical connector of claim 22 wherein thesecond surface of the housing includes at least one device sitecorresponding to the second circuit member.
 29. The electrical connectorof claim 22 wherein the second ends of the electrical contact membershave a shape that corresponds to a shape of the terminals on the secondcircuit member.
 30. The electrical connector of claim 22 wherein thesecond ends of the electrical contact members are capable of engagingwith a connector member selected from the group consisting of a flexiblecircuit, a ribbon connector, a cable, a printed circuit board, a ballgrid array (BGA), a land grid array (LGA), a plastic leaded chip carrier(PLCC), a pin grid array (PGA), a small outline integrated circuit(SOIC), a dual in-line package (DIP), a quad flat package (QFP), aleadless chip carder (LCC), a chip scale package (CSP), or packaged orunpackaged integrated circuits.
 31. The electrical connector of claim 22wherein the electrical contact members are one of a homogeneous materialor a multi-layered construction.
 32. The electrical connector of claim22 wherein the electrical contact members have a cross-sectional shapeselected from one of circular, oval, polygonal, and rectangular.
 33. Theelectrical connector of claim 22 wherein a portion of the flexiblecircuit member is bonded to the first surface of the housing.
 34. Theelectrical connector of claim 22 wherein the electrical contact membersare electrically coupled to the flex circuit using one or more of acompressive force, solder, a wedge bond, a conductive adhesive, anultrasonic bond and a wire bond.
 35. The electrical connector of claim22 wherein the second ends of at least two of the electrical contactmembers extend beyond the second surface of the housing by a differentamount.
 36. The electrical connector of claim 22 wherein electricalcontact members have a larger cross section proximate the first end thanat the second end.
 37. The electrical connector of claim 22 wherein theplurality of through holes are arranged in a two-dimensional array. 38.The electrical connector of claim 22 wherein the compliant encapsulatingis interposed between a portion of the through holes and a portion ofthe electrical contact members.
 39. The electrical connector of claim 22wherein the second ends of the electrical contact members comprises oneor more of die level test probes, wafer probes, and printed circuitboard probes.
 40. The electrical connector of claim 22 comprising: asecond housing having a plurality of through holes extending between afirst surface and a second surface, each of the through holes defining acentral axis; a plurality of elongated electrical contact memberspositioned in at least a portion of the through holes and oriented alongthe central axes, the electrical contact members having first endsextending above the first surface adapted to couple electrically withthe terminals on the flexible circuit member, and second ends extendingabove the second surface to couple electrically with a third circuitmember.
 41. The electrical connector of claim 40 wherein the firstsurface of the first housing is positioned opposite the first surface ofthe second housing.
 42. The electrical connector of claim 40 wherein thefirst housing and the second housing are arranged in a stackedconfiguration.
 43. An electrical connector comprising: a flexiblecircuit member having a plurality of terminals; a first housing having aplurality of through holes extending between a first surface and asecond surface, each of the through holes defining a central axis; aplurality of elongated electrical contact members positioned in at leastsome of the through holes and oriented along the central axes, theelectrical contact members having first ends extending above the firstsurface that are fixedly bonded to, and electrically coupled with theterminals on the flexible circuit member, the flexible circuit membercontrolling movement of the electrical contact members along theirrespective central axes, and second ends extending above the secondsurface to couple electrically with the second circuit member; and acompliant encapsulating material elastically bonding the electricalcontact members to the housing.
 44. A method of making an electricalinterconnect for electrically coupling terminals on a flexible circuitmember with terminals on a second circuit member, comprising the stepsof: providing a housing having a plurality of through holes extendingbetween a first surface and a second surface, each of the through bolesdefining a central axis; positioning a plurality of elongated electricalcontact members in at least some of the through boles oriented along thecentral axes, the electrical contact members having first ends extendingabove the first surface; positioning a flexible circuit member toelectrically couple the terminals with the first ends of the electricalcontact members; interposing a compliant encapsulating material betweena portion of the through holes and a portion of the electrical contactmembers to control movement of the electrical contact members alongtheir respective central axes; and positioning a compliant materialalong a surface of the flexible circuit member opposite at least one ofthe terminals of the flexible circuit member.
 45. The method of claim 44comprising the step of attaching the first ends of the electricalcontact members to the terminals on the flexible circuit member.
 46. Themethod of claim 44 comprising the step of singulating at least one ofthe terminals on the flexible circuit member.
 47. A method of making anelectrical interconnect for electrically coupling terminals on aflexible circuit member with terminals on a second circuit member,comprising the steps of: providing a housing having a plurality ofthrough holes extending between a first surface and a second surface,each of the through holes defining a central axis; positioning aplurality of elongated electrical contact members in at least some ofthe through holes oriented along the central axes, the electricalcontact members having first ends extending above the first surface;elastically bonding the electrical contact members to the housing with acompliant encapsulating material; positioning a flexible circuit memberto electrically couple the terminals with the first ends of theelectrical contact members; and fixedly bonding the first ends of theelectrical contact members to the terminals.
 48. The method of claim 47comprising the step of interposing a compliant encapsulating materialbetween a portion of the through holes and a portion of the electricalcontact members to control movement of the electrical contact membersalong their respective central axes.
 49. The method of claim 47comprising the step of positioning a compliant material along a surfaceof the flexible circuit member opposite at least one of the terminals ofthe flexible circuit member.